I think there’s a middle ground where “it depends on the kid” and “overprotection.”
For example, I hate scary movies. I hate gory movies. I don’t watch them on my own, so there’s no way I’m going to sit down and watch them with my kids. It has nothing to do with being over-protective... I simply don’t like them and as a result, I’m not likely to choose that as a shared experience thing. I figure not watching a movie I don’t want to watch is my perk for being an adult. I have to pay bills, work, get up early, but darn it, I can watch “Downton Abbey” a gabillion times and I don’t have to watch what I don’t want to watch.
Beyond that, for things that ride my personal threshold... For example, “Jurassic Park” or our recent “should we or shouldn’t we” movie choice (“Ghostbusters”), we rely on best judgement based on the kids.
My youngest (8) I think is about where he should be for violence and scariness tolerance, so we will do “Jurassic World” and tell him when to look away, or “Ghostbusters” but tell him about a jump-scare incoming. Things like “Star Wars,” with the exception of the back half of Episode 3 and one scene in A New Hope, he can watch with no issues.
Our oldest (11)? He is like me... He has an exceptionally low threshold for being scared. “Jurassic World” he will watch but not particularly enjoy. It’s too scary. I guess he tried watching the kid’s TV show “Goosebumps” and he wasn’t having it. His threshold for being scared is “The Twilight Zone” and that’s about it. He won’t even do Hanuted Mansion at Disney. Too scary.
Our middle guy (9) has an exceptionally high threshold, higher than all of us. He likes being scared (but almost never is), finds gore in movies interesting because he knows it’s fake but wants to see if he can figure out how they do it. Even as a kid, he’d do Haunted Mansion at Disney and then at the end he’s asking how it was done, or telling us how it’s done. He’d probably love watching “The Meg,” and then the whole ride home he’d tell us how they did it, what facts they got wrong, facts they didn’t cover, and then he’d move along with life. Heck, he’d watch “It” if we let him and let us know all the ways it was throughly unrealistic and how they filmed it. He’s an analytical problem solver. Movies are fantasy, guts are a part of all of us, everybody gets scared. While his brothers are crying and scared out of their minds in the closet, he’s standing outside the door telling them a point-by-point rundown on why they have nothing to worry about.
Now, I don’t think it’s particularly appropriate to show a child under 10 (or maybe even 14-16) “It” and I have a hard time justifying how any parent could say otherwise... It’s a horror movie based on the work of a horror author that was highly controversial for its violence, sexual content, and subject matter. I put it as a top tier shock and horror gore film, out of the realm of enjoyment for a significant number of adults, let alone kids. Movies like “The Meg” or “Jaws,” I’d screen first. I know nothing about “The Meg,” but based off of my memories of “Jaws” being a hair above my personal gore threshold, certainly two of my three wouldn’t see it, but one likely would. Movies a tier below that (“Jurassic Park,” or most Marvel movies) they’d all watch it but be told when to look away.